This invention relates generally to refrigeration systems and, more particularly, to a method and apparatus for mounting a distributor and thermal expansion valve assembly in a refrigeration system.
In air conditioning and refrigeration systems it is common to maintain a certain degree of superheat in the refrigerant passing from the evaporator to the compressor in order to protect the compressor from damage that can occur by liquid refrigerant passing therethrough. This is accomplished by using a thermal expansion valve (TXV) upstream of the evaporator coil, with an associated temperature sensor or bulb for sensing the temperature of the refrigerant passing from the evaporator coil.
In one type of air conditioner that is used in combination with a furnace, an A-coil is provided with a piping assembly which includes the thermal expansion valve being attached to the liquid line and, in close proximity, the sensor bulb being attached to the outlet header.
In order for the bulb to provide accurate temperature readings, it is necessary to mount the bulb in such a way as to ensure a fixed and firm engagement with the header and to isolate the bulb from the surroundings. The first function had generally been served by one or more clamps and the second function has generally been accomplished by providing some kind of protective cover over the area in which the bulb is secured to the outlet line. The most common type of insulation that is provided around the bulb of an A-coil is a foam tape that is wrapped around the clamp. The problems with this approach are twofold. First, it is difficult to access that portion of the piping assembly and to obtain a firm and proper securing of the clamp and bulb to the outlet header. Secondly, the wrapping of the insulation tape will vary greatly with the serviceman applying it and may well not be sufficient to ensure good isolation of the bulb that would result in accurate readings.
Other types of temperature sensors are also used to sense refrigerant temperatures in various lines of a refrigeration system for purposes of control and/or protection of the system. These sensors are subject to the same problems as discussed hereinabove.
Another problem that occurs with A-coil piping assemblies is that of the distributor assembly, which includes both the TXV and the liquid line leading to it, vibrating in shipping or operational use and eventually causing failure of the liquid line. This problem is presently addressed by a separate clamp that rigidly interconnects the liquid line to the outlet header.